Great success has been achieved in the exploration of oil-rich sags, mainly Bohai Bay Basin. The size of oil reservoirs in the mature exploration areas have been basically defined, but oil-rich sags still have abundant oil resources. Nowadays, we find oil resources unbalanced and encounter a technical bottleneck in how to search for remaining oil resources. Concerning the problems above, the present invention aims to provide a method for overall exploration of a mature exploration area of oil-rich sags.